1. Technical Field
The present invention relates to a platform that can be used to deliver a tool to a downhole location in a well substantially filled with a fluid. The platform is also referred to as a “float shoe.” It provides a controlled descent into the drill hole by metering drilling fluid in the hole through a plurality of ports. The platform is not coupled to the surface by wire or tubing.
2. Description of the Related Art
Various tools are needed during the completion of a well. Once the casing has been cemented into place, for example, a perforation gun is then lowered into the well to the desired depth and discharged. The explosive charges perforate the casing, cement, and adjacent formation. The perforation gun is lowered into the well at the end of a wire, or at the end of rigid or flexible tubing. In either scenario, a rig must be used to lower the tool into the well. The cost of this additional equipment obviously raises the overall cost of completing the well.
FIG. 1 illustrates an example of the prior art method 100 of lowering a tool into a well. A borehole 12 is made into the ground 10. The hole penetrates a formation of interest 18. To stabilize the walls of the hole 12, a casing 14 is lowered into the hole and cement is pumped into the annular space between the casing and hole. It is common for fluids to fill the cased well. These fluids include drilling fluids that are used in the drilling process. The fluids can also include hydrocarbons that leak from the formation 18. The fluid 16 might also contain salt water, as this is commonly encountered when drilling wells. This mixture of fluids has a unique viscosity based upon the constituent elements of the fluid. The tool 40 is shown being lowered into the well by tubing that is in turn being lowered by a derrick 102. The derrick 102 has a crown block 108 and pulley system 106. A cable 104 is used to manipulate, lift, and lower the tubing into the well. This is just one illustration of a generic configuration used for delivering a tool to a downhole location.
There are many types of tools that can be lowered into a well. For example, the tool could be a perforation gun used to perforate the casing adjacent to the formation 18. Another tool might be a packer used to isolate one part of the well from another. Different tools are used during the drilling of a well, its completion and during the production phase of the well. In each situation, the cost of using the tool adds to the overall cost of the well. Much of this cost is attributable to the cost of construction a derrick to support the tubing used to convey the tools. A need exists for a simpler, less expensive method of delivering a tool safely to a downhole location.